It’s summer solstice time for us in the Northern Hemisphere. This solstice occurs at the instant the sun reaches its most northerly point on the celestial sphere, the imaginary sphere of stars surrounding Earth. In 2018, the June solstice happens at 10:07 UTC; translate to your time zone. Many – perhaps you – will celebrate this solstice sunrise, or next year’s solstice sunrise, at Stonehenge. Why?
Stonehenge was built in three phases between 3,000 B.C. and 1,600 B.C. and its purpose remains under study. However, it’s known that if you stand in just the right place inside the Stonehenge monument on the day of the northern summer solstice, facing north-east through the entrance towards a rough hewn stone outside the circle – known as the Heel Stone – you will see the sun rise above the Heel Stone, as illustrated in the image at the top.
In the Northern Hemisphere at this time of year, the sun is shining on us most directly at midday. Except at high northerly latitudes, above the Arctic Circle – where daylight is continuous for many months – the day on which the summer solstice occurs is the day of the year with the longest period of daylight. Meanwhile, it is the shortest day for Earth’s Southern Hemisphere.
At the northern summer solstice – always around June 20 – the sun’s path stops moving northward in the sky. For us in the northern hemisphere, it’s the day on which the days stop growing longer and will soon begin to shorten again. For this reason, in festivals and celebrations across this hemisphere of Earth, the summer solstice is a time of celebration.
Stonehenge is tied to the winter solstice, too. At Stonehenge in England on the day of the northern winter solstice (always around December 20), people watch as the sun sets in the midst of three great stones – known as the Trilithon – consisting of two large vertical stones supporting a third, horizontal stone across the top.
In the case of Stonehenge, this great Trilithon faces outwards from the center of the monument, with its smooth flat face turned toward the midwinter sun. In fact, the primary axes of Stonehenge seems to have been carefully aligned on a sight-line pointing to the winter solstice sunset.
This Stonehenge monument – built in 3,000 to 2,000 BC – shows how carefully our ancestors watched the sun. Astronomical observations such as these surely controlled human activities such as the mating of animals, the sowing of crops and the metering of winter reserves between harvests. Stonehenge is perhaps the most famous of of the ancient astronomical monuments found around the world.
When Stonehenge was first opened to the public it was possible to walk among the stones – even climb on them.
The stones were roped off in 1977 as a result of serious erosion. Today, visitors to the monument are not permitted to touch the stones, but, if you go, you will be able to walk around the monument from a short distance away. Visitors can also make special bookings to access the stones throughout the year.
Bottom line: If you stand at just the right spot inside the Stonehenge monument on the day of the northern summer solstice, facing northeast through the entrance towards a rough hewn stone outside the circle – known as the Heel Stone – you will see the sun rise above the Heel Stone. The 2018 June solstice comes on June 21 at 10:07 UTC; translate to your time zone.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.